The nuclear hormone receptor (NHR) family of transcription factors bind low molecular weight ligands and either stimulates or represses transcription. See, e.g., V. LAUDET ET AL., THE NUCLEAR RECEPTOR FACTS BOOK, 345, (2002). NHRs stimulate transcription by binding to DNA and inducing transcription of specific genes. NHRs may also stimulate transcription by not binding to DNA itself, rather they may modulate the activity of other DNA binding proteins. Stocklin, E., et al., Nature 383:726–8 (1996). The process of stimulation of transcription is called transactivation. NHRs repress transcription by interacting with other transcription factors or coactivators and inhibiting the ability of these other transcription factors or coactivators from inducing transcription of specific genes. This repression is called transrepression. For a review of this topic, see generally V. Laudet, supra, beginning at 42.
The glucocorticoid receptor (GR) is a member of the nuclear hormone receptor family of transcription factors, and a member of the steroid hormone family of transcription factors. Affinity labeling of the glucocorticoid receptor protein allowed the production of antibodies against the receptor which facilitated cloning the glucocorticoid receptors. For results in humans see Weinberger, et al., Science 228, 640–742, (1985); Weinberger, et al., Nature, 318, 670–672 (1986) and for results in rats see Miesfeld, R., Nature, 312, 779–781, (1985).
Glucocorticoids which interact with GR have been used for over 50 years to treat inflammatory diseases. It has been clearly shown that glucocorticoids exert their anti-inflammatory activity via the inhibition by GR of the transcription factors NF-kappaB and AP-1. This inhibition is termed transrepression. It has been shown that the primary mechanism for inhibition of these transcription factors by GR is via a direct physical interaction. This interaction alters the transcription factor complex and inhibits the ability of NF-kappaB and AP-1 to stimulate transcription. See Jonat, C., et al., Cell, 62, 1189 (1990); Yang-Yen, H. F., et al,. Cell, 62, 1205 (1990); Diamond, M. I. et al., Science 249, 1266 (1990); and Caldenhoven, E. et al., Mol. Endocrinol., 9, 401 (1995). Other mechanisms such as sequestration of co-activators by GR have also been proposed. See Kamer Y, et al., Cell, 85, 403 (1996); and Chakravarti, D. et al., Nature, 383, 99 (1996). NF-kappaB and AP-1 play key roles in the initiation and perpetuation of inflammatory and immunological disorders. See Baldwin, A S, Journal of Clin. Investigation, 107, 3 (2001); Firestein, G. S., and Manning, A. M., Arthritis and Rheumatism, 42, 609 (1999); and Peltz, G., Curr. Opin, in Biotech. 8, 467 (1997). NF-kappaB and AP-1 are involved in regulating the expression of a number of important inflammatory and immunomodulatory genes including: TNF-alpha, IL-1, IL-2, IL-5, adhesion molecules (such as E-selectin), chemokines (such as Eoxtaxin and Rantes), Cox-2, and others.
In addition to causing transrepression, the interaction of a glucocorticoid with GR can cause GR to induce transcription of certain genes. This induction of transcription is termed transactivation. Transactivation requires dimerization of GR and binding to a glucocorticoid response element (GRE).
Recent studies using a transgenic GR dimerization defective mouse which cannot bind DNA have shown that the transactivation (DNA binding) activities of GR could be separated from the transrepressive (non-DNA binding) effect of GR. These studies also indicate that many of the side effects of glucocorticoid therapy are due to the ability of GR to induce transcription of various genes involved in metabolism, whereas, transrepression, which does not require DNA binding leads to suppression of inflammation. See Tuckermann, J. et al., Cell, 93, 531 (1998) and Reichardt, H M, EMBO J., 20, 7168 (2001).
The art is in need of modulators of NHRs. A modulator of an NHR may be useful in treating NHR-associated diseases, that is diseases associated with the expression products of genes whose transcription is stimulated or repressed by NHRs. For instance, the art is in need of modulators of NHRs that inhibit AP-1 and NFκB, as such compounds would be useful in the treatment of inflammatory and immune diseases and disorders such as osteoarthritis, rheumatoid arthritis, multiple sclerosis, asthma, inflammatory bowel disease, transplant rejection and graft vs. host disease.
Particularly concerning GR, although glucocorticoids are potent anti-inflammatory agents, their systemic use is limited by side effects. A compound that retained the anti-inflammatory efficacy of glucocorticoids while minimizing the side effects such as diabetes, osteoporosis and glaucoma would be of great benefit to a very large number of patients with inflammatory diseases.
Additionally concerning GR, the art is in need of compounds that antagonize transactivation. Such compounds may be useful in treating metabolic diseases associated with increased levels of glucocorticoid, such as diabetes, osteoporosis and glaucoma.
Additionally concerning GR, the art is in need of compounds that cause transactivation. Such compounds may be useful in treating metabolic diseases associated with a deficiency in glucocorticoid. Such diseases include Addison's disease.